1. Field of the Invention
This invention is directed to inflatable packers used in wellbore operations, to methods of using them and, in certain particular aspects, to drillable inflatable packers, methods of using them, and cementing methods using such packers.
2. Description of the Related Art
In many wellbore operations an inflatable packer is positioned in a wellbore and retrieved (e.g. but not limited to oil well wellbores, gas well wellbores, and bores in coal beds). It can be difficult to drill or mill conventional packers which have various hard metal parts. This can be a serious problem, particularly if a retrievable inflatable packer cannot be retrieved and must be drilled through or milled out. In drilling various wells, e.g. geothermal wells, it is common to encounter lost circulation zones that absorb drilling fluids. Prior to resuming normal drilling operations, lost circulation zones are plugged off. In one prior art plugging method, a retrievable packer is set above the zone, and cement is pumped through the packer and into the zone. If pumped cement flows in channels in the formation, routes around and above the packer, and sets, retrieval of the packer may not be possible. In certain prior art methods a non-retrievable packer and related apparatus are used so that, following successful plugging of a lost circulation zone, further wellbore operations conducted through the non-retrievable packer are limited by the restricted diameter of bores through the non-retrievable packer and related apparatus.
There has long been a need for an efficient packer which can be used effectively in a bore or borehole during wellbore operations, including but not limited to cementing operations. There has long been a need, recognized by the present inventors, for such a packer that can be drilled out or milled out rather than retrieved so that the entire diameter of a borehole can be reclaimed for subsequent operations. There has long been a need for such a packer and methods of its use for effectively
The present invention, in certain embodiments, provides a drillable inflatable packer and methods of its use. The present invention, in certain embodiments, provides a cementing method using such a packer and an associated packer setting and inflation system.
In one aspect a system according to the present invention includes a selectively settable drillable inflatable packer and a running system with a valve assembly for controlling flow to the packer and to other parts of the system and a lower valve through which cement is flowable into the annulus outside the system and below the packer. Initially fluid (e.g., but not limited to, water, brine, or cement) is pumped through the system and the valve assembly into the packer. Following proper inflation of the packer to seal off the annulus in the borehole between the system""s exterior and the borehole""s interior, and following setting of the cement, fluid (e.g., but not limited to cement, brine, or water) is pumped through the system, through the packer, through the lower valve and into the formation to plug it off for further operations, e.g., but not limited to, drilling operations or operations above and/or below the lost circulation zone. Upon completion of the plugging operations, the running system is disengaged from the packer (and from associated apparatus) and the running system is then removed from the borehole, leaving the drillable inflated packer in place. Optionally, the borehole can then be reclaimed for operations below the packer by cutting through (e.g. by drilling or milling) the packer, cement, and lower valve apparatus.
In certain aspects, the present invention provides an inflatable packer with a packer body, an inflatable bladder mounted around the packer body, and a plurality of ribs mounted around the inflatable bladder. The packer body, the inflatable bladder, and the ribs may be made of drillable material. A lower valve apparatus used with the packer may also be made of drillable material.
In certain aspects, the present invention provides a method for reclaiming a borehole extending from an earth surface into the earth, part of which is in a lost circulation zone, the method including closing off the borehole to fluid flow above the lost circulation zone by installing a packer system with an inflatable packer element and a valve apparatus in the borehole above the lost circulation zone, inflating the inflatable packer element with cement, and allowing the cement to set so that the inflatable packer and the valve apparatus effectively seal off the borehole to fluid flow.
What follows are some of, but not all, the objects of this invention. In addition to the specific objects stated below for at least certain preferred embodiments of the invention, other objects and purposes will be readily apparent to one of skill in this art who has the benefit of this invention""s teachings and disclosures. It is, therefore, an object of at least certain preferred embodiments of the present invention to provide new, useful, unique, efficient, nonobvious drillable, inflatable packers and methods of their use;
Such a packer useful in well operations, including, but not limited to, cementing operations;
Such a packer that is easily drilled through or milled out from the borehole, in one aspect, so that the entire diameter of the borehole is reclaimed without an area limited by the restricted diameter of other wellbore apparatus;
Such a packer useful in operations for plugging off a lost circulation zone;
Such a packer that is effective in open hole operations or within a tubular, e.g. in cased hole operations;
Such a packer useful in a cementing operation having a lower valve apparatus that can be selectively opened, cemented through, and selectively closed so that pressure is held both above and below it; and
Such a packer useful in operations in oil wells, gas wells, water wells, and bores in coal beds.
Certain embodiments of this invention are not limited to any particular individual feature disclosed here, but include combinations of them distinguished from the prior art in their structures and functions. Features of the invention have been broadly described so that the detailed descriptions that follow may be better understood, and in order that the contributions of this invention to the arts may be better appreciated. There are, of course, additional aspects of the invention described below and which may be included in the subject matter of the claims to this invention. Those skilled in the art who have the benefit of this invention, its teachings, and suggestions will appreciate that the conceptions of this disclosure may be used as a creative basis for designing other structures, methods and systems for carrying out and practicing the present invention. The claims of this invention are to be read to include any legally equivalent devices or methods which do not depart from the spirit and scope of the present invention.
The present invention recognizes and addresses the previously-mentioned problems and long-felt needs and provides a solution to those problems and a satisfactory meeting of those needs in its various possible embodiments and equivalents thereof. To one skilled in this art who has the benefits of this invention""s realizations, teachings, disclosures, and suggestions, other purposes and advantages will be appreciated from the following description of preferred embodiments, given for the purpose of disclosure, when taken in conjunction with the accompanying drawings. The detail in these descriptions is not intended to thwart this patent""s object to claim this invention no matter how others may later disguise it by variations in form or additions of further improvements.